Daniel@0: function L = log_marg_prob_node(CPD, self_ev, pev, usecell)
Daniel@0: % LOG_MARG_PROB_NODE Compute sum_m log P(x(i,m)| x(pi_i,m)) for node i (tabular)
Daniel@0: % L = log_marg_prob_node(CPD, self_ev, pev)
Daniel@0: %
Daniel@0: % This differs from log_prob_node because we integrate out the parameters.
Daniel@0: % self_ev(m) is the evidence on this node in case m.
Daniel@0: % pev(i,m) is the evidence on the i'th parent in case m (if there are any parents).
Daniel@0: % (These may also be cell arrays.)
Daniel@0: 
Daniel@0: ncases = length(self_ev);
Daniel@0: sz = CPD.sizes;
Daniel@0: nparents = length(sz)-1;
Daniel@0: assert(ncases == size(pev, 2)); 
Daniel@0: 
Daniel@0: if nargin < 4
Daniel@0:   %usecell = 0;
Daniel@0:   if iscell(self_ev)
Daniel@0:     usecell = 1;
Daniel@0:   else
Daniel@0:     usecell = 0;
Daniel@0:   end
Daniel@0: end
Daniel@0: 
Daniel@0: 
Daniel@0: if ncases==0
Daniel@0:   L = 0;
Daniel@0:   return;
Daniel@0: elseif ncases==1  % speedup the sequential learning case
Daniel@0:   CPT = CPD.CPT;
Daniel@0:   % We assume the CPTs are already set to the mean of the posterior (due to bayes_update_params)
Daniel@0:   if usecell
Daniel@0:     x = cat(1, pev{:})';
Daniel@0:     y = self_ev{1};
Daniel@0:   else
Daniel@0:     %x = pev(:)';
Daniel@0:     x = pev;
Daniel@0:     y = self_ev;
Daniel@0:   end
Daniel@0:   switch nparents
Daniel@0:    case 0, p = CPT(y);
Daniel@0:    case 1, p = CPT(x(1), y);
Daniel@0:    case 2, p = CPT(x(1), x(2), y);
Daniel@0:    case 3, p = CPT(x(1), x(2), x(3), y);
Daniel@0:    otherwise,
Daniel@0:     ind = subv2ind(sz, [x y]);
Daniel@0:     p = CPT(ind);
Daniel@0:   end
Daniel@0:   L = log(p);
Daniel@0: else
Daniel@0:   % We ignore the CPTs here and assume the prior has not been changed
Daniel@0:   
Daniel@0:   % We arrange the data as in the following example.
Daniel@0:   % Let there be 2 parents and 3 cases. Let p(i,m) be parent i in case m,
Daniel@0:   % and y(m) be the child in case m. Then we create the data matrix
Daniel@0:   % 
Daniel@0:   % p(1,1) p(1,2) p(1,3)
Daniel@0:   % p(2,1) p(2,2) p(2,3)
Daniel@0:   % y(1)   y(2)   y(3)
Daniel@0:   if usecell
Daniel@0:     data = [cell2num(pev); cell2num(self_ev)]; 
Daniel@0:   else
Daniel@0:     data = [pev; self_ev];
Daniel@0:   end
Daniel@0:   %S = struct(CPD); fprintf('log marg prob node %d, ps\n', S.self); disp(S.parents)
Daniel@0:   counts = compute_counts(data, sz);
Daniel@0:   L = dirichlet_score_family(counts, CPD.dirichlet);
Daniel@0: end
Daniel@0: 
Daniel@0: